P01D5: Cylinder 6 Injection Timing Performance - Over Retarded
What to do
Mention any rattle from the engine for a second or two after startup, even if it has been there for years and you had stopped noticing. That is the classic sign of a worn timing chain, which shifts the timing on the cylinders furthest from the front — exactly this one — and produces this fault with perfectly good injectors.
Ask for fuel rail pressure to be checked under load. This cylinder is at the end of the rail and feels a pressure shortfall first.
Say whether the roughness is worse from cold, which points at compression or a glow plug instead.
Ask for the chain to be assessed before an injector is replaced on a high-mileage six-cylinder engine.
What this code means
Combustion on cylinder 6 is happening later than the module commanded.
On a straight six this is the last cylinder and the furthest from both the fuel pump and the timing drive — two independent reasons for a late burn to appear here first.
The fuel reason is pressure. The end of a long rail sees each pressure wave last and slightly damped, so a rail marginally short of pressure starves this cylinder before the others. Fuel injected at low pressure atomises coarsely and takes longer to ignite.
The mechanical reason is chain stretch. A worn chain changes the crank-to-cam relationship progressively along the engine, so the cylinders furthest from the drive drift most. On a high-mileage straight six, timing codes creeping along the block from the far end are a chain rather than a set of injectors.
Both explanations produce a late burn on this cylinder and neither is fixed by an injector. Check rail pressure under load and assess chain wear before removing anything.
Where both are sound, the ordinary causes apply — a slow-opening or restricted injector, low compression on that cylinder, or a failed glow plug making the cold burn late.
A rattle for a second or two on startup is the classic sign of a worn chain tensioner, and it is worth asking about explicitly, because owners tend to accept it as normal long before it sets a code.
Likely causes
Start here
- Stretched timing chain · specialist
- Low fuel pressure · moderate
- Failed fuel injector · specialist
Less common
- Worn timing chain tensioner or guide · specialist
- Low engine compression · specialist
Symptoms
Components involved
Information, not instruction
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